/*
  Date: 2 Feb 2016
  Author: Vasil Zlatanov
*/

#include "2048.h"
#include <stdio.h>
#include <stdlib.h> //needed for random
#include <time.h>   // needed to for "random" seed

void init(int board[SIZE][SIZE])
{
	int x, y;
	// Load start config
	for (x = 0; x < SIZE; x++) {
		for (y = 0; y < SIZE; y++) {
			board[x][y] = 0;
		}
	}
	board[SIZE - 1][SIZE - 1] = 1;
}

int move(int direction, int board[SIZE][SIZE]){
	int done;
	switch(direction) {
		case 3 :
			done = slideLeft(board);
			break;
		case 2 :
			done = slideDown(board);
			break;
		case 1 :
			done = slideUp(board);
			break;
		case 0 :
			done = slideRight(board);
			break;
		default :
			done = 0;
	}
	return done;
}

int slideLeft(int board[SIZE][SIZE])
{
	int done;
	rotate(board);
	done = slideUp(board);
	rotate(board);
	rotate(board);
	rotate(board);
	return done;
}

int slideRight(int board[SIZE][SIZE])
{
	int done;
	rotate(board);
	rotate(board);
	rotate(board);
	done = slideUp(board);
	rotate(board);
	return done;
}

int slideUp(int board[SIZE][SIZE])
{
	int done = 0;
	int x;
	for (x = 0; x < SIZE; x++) {
		done |= push(board[x]);
	}
	return done;
}

int slideDown(int board[SIZE][SIZE])
{
	int done;
	rotate(board);
	rotate(board);
	done = slideUp(board);
	rotate(board);
	rotate(board);
	return done;
}

int push(int array[SIZE])
{
	int x, n, stop = 0, done = 0;
	for (x = 1; x < SIZE; x++) {
		if (array[x] != 0) {	// make sure there is something in box
			done = 2;	// don't exit loop until we determine if there is a move
			for (n = x - 1; done == 2; n--) {
				if (array[n] != 0) {	// if box has number in it
					if (array[n] == array[x]) {	// same so merge
						array[n]++;	// increase by power of two
						stop = n + 1;	// avoid double merge such as 2 2 0 4
						array[x] = 0;
						done = 1;
					} else {	// not the same so move just below
						if (n + 1 != x) {
							array[n + 1] = array[x];
							array[x] = 0;
							done = 1;
						} else {
							done = 0;	// we can't slide any further
						}
					}
				} else {
					if (n == stop) {
						array[stop] = array[x];
						array[x] = 0;
						done = 1;
					}
				}
			}
		}
	}
	return done;
}

void rotate(int board[SIZE][SIZE])
{
	int x, y, n = SIZE, temp;
	for (x = 0; x < n / 2; x++) {
		for (y = x; y < n - x - 1; y++) {
			temp = board[x][y];
			board[x][y] = board[y][n - x - 1];
			board[y][n - x - 1] = board[n - x - 1][n - y - 1];
			board[n - x - 1][n - y - 1] = board[n - y - 1][x];
			board[n - y - 1][x] = temp;
		}
	}
}

int gameover(int board[SIZE][SIZE])
{
	int x, y;
	int nofree = 1;
	for (x = 0; x < SIZE - 1; x++) {
		for (y = 0; y < SIZE - 1; y++) {
			if (board[x][y] == 0) {
				nofree = 0;	// means we have a free square
			}
		}
	}

	if (nofree) {
		// Check if there is any moves horizontaly or vertically;
		for (x = 0; x < SIZE - 1; x++) {
			for (y = 0; y < SIZE - 1; y++) {
				if ((board[x][y] == board[x][y + 1]) ||
				    (board[x][y] == board[x + 1][y])) {
					return 0;
				}
			}
		}
	}
	return nofree;
}

void add2(int board[SIZE][SIZE])
{
	int x, y, r, pos = 0, free[SIZE * SIZE][2];
	for (x = 0; x < SIZE; x++) {
		for (y = 0; y < SIZE; y++) {
			if (board[x][y] == 0) {
				free[pos][0] = x;
				free[pos][1] = y;
				pos++;
			}
		}
	}
	if (free > 0) {
		r = rand() % pos;
		board[free[r][0]][free[r][1]] = 1;
	}
}